The Spanish giants exercised their right to re-sign their former player after two years with Juventus, but according to Morata, that did not stop Chelsea from making him a "very good offer" to make the switch to Stamford Bridge.
The 23-year-old told Bild: "They said that they have me in their plans, and that was always a dream of mine.
"Chelsea showed the most interest and it was a very good offer this time. I would have been the most expensive Spanish player ever."
Morata has started the new season with two goals from six appearances in all competitions.